This invention relates to an improved apparatus for cleaning large tanks or vessels, such as, for example, automotive and railway tank cars. A closely related apparatus is disclosed and claimed in U.S. Pat. No. 4,244,523, issued to Bruce T. Hooper on Jan. 13, 1981, for an Apparatus for Cleaning Tanks or Vessels, which is hereby incorporated by reference.
It is imperative in many industrial operations to thoroughly clean the interior surfaces of large tanks or vessels. Such cleaning is usually done by manual labor. But, manual cleaning is a tedious and time consuming task. Furthermore, manual cleaning often exposes the worker to toxic or corrosive substances and vapors and otherwise creates a hazardous environment for the worker. Thus, automatic cleaning apparatus are desirable.
The phosphoric acid industry presents a typical large tank or vessel cleaning situation. Phosphoric acid is shipped in rubber-lined automotive or railway tank cars. Gypsum and other solids precipitate during the period of transportation from the acid manufacturing plant to the ultimate destination. As a result of such precipitation, a sticky, acid-rich sludge is deposited on the sides and bottom of each tank car. Because the amount of sludge present in each tank car is often substantial, standard industry practice is to clean or remove the sludge from the interior surface of each tank car after each round trip made by that car.
The automotive and railway tank cars which are used for phosphoric acid shipments usually are of the single compartment type. Occasionally, phosphoric acid is shipped in tank cars having a plurality of interior compartments. Such tank cars are widely used in other industries, such as the petroleum industry. With such tank cars, a separate access opening is provided for each of the interior compartments. Normally, the access openings of such tank cars are smaller than the access openings of single compartment tank cars.
Various apparatus for cleaning automotive and railway tank cars and other large tanks and vessels are well known in the art. Nevertheless, prior to the Applicant's invention of the apparatus disclosed and claimed in U.S. Pat. No. 4,244,523, known apparatus were either too large or too heavy, or both, for one worker to conveniently move the apparatus from location to location and position it over and in the access opening at the top of the tank or vessel to be cleaned. And, known apparatus were incapable of thoroughly cleaning the entire interior surface of a typical large tank or vessel, such as, for example, an automotive or railway tank car. Furthermore, known apparatus were either too costly to manufacture or cleaned too slowly, or both, for routine cleaning of large tanks and vessels.
The apparatus disclosed and claimed in U.S. Pat. No. 4,244,523 eliminated many of the disadvantages inherent in known apparatus for cleaning large tanks and vessels. That apparatus is both light enough and small enough to enable one worker to conveniently move it from location to location. And, that apparatus is small enough to be positioned over and in the main dome access opening of most single compartment railway tank cars and the access opening of many single compartment automotive tank cars and other large tanks and vessels. With such tanks and vessels, that apparatus is capable of thoroughly cleaning the entire interior surface of the tank or vessel. Furthermore, because it is relatively inexpensive to manufacture and is capable of relatively rapid cleaning, that apparatus is suitable for routine cleaning of such tanks and vessels.
While the apparatus disclosed and claimed in U.S. Pat. No. 4,244,523 has many advantages and benefits, it cannot be used to clean typical multi-compartment automotive tank cars and other large tanks and vessels having relatively small access openings. That apparatus has a tiltable frame, pivotedly mounted to a fixed support frame, and a wash nozzle assembly, pivotedly mounted to the tiltable frame, which are continuously moved to direct cleaning liquid spray jets along two axes of the tank or vessel to be cleaned. It can be appreciated from an examination of FIGS. 3-6 of U.S. Pat. No. 4,244,523 that a relatively large access opening in the tank or vessel to be cleaned is required for continuous movement of both the tiltable frame and the wash nozzle assembly of that apparatus.
It is desirable to have an apparatus which can be used to clean large tanks and vessels having relatively small access openings. It is also desirable to have an apparatus which achieves this capability without sacrificing the advantages which are inherent in the apparatus disclosed and claimed in U.S. Pat. No. 4,244,523.